The production of hydrocarbon fluids from subterranean reservoirs through wells drilled into the formation often results in the inadvertent production of contaminants or trace elements washed out of the formation by the production flow. Mercury, in particular, is known as a contaminant of hydrocarbon production in many geographical areas.
The typical concentrations of mercury in the gas phase production streams ranges from 50 to 180 micro gram/standard cubic meter of gas. In liquid phase production the level of concentrations of mercury varies typically from 10 to 1000 parts per billion (ppb). In the known reservoirs mercury occurs predominantly in elemental form. It can also be found in ionic form or as an organic compound.
When present in sufficient concentration, the contaminated production becomes unsuitable as feed flow for downstream refineries and the contaminant has to be removed before entering the refining process. The various known mercury removal processes can be categorized in accordance with the underlying principle used in the process as:
1) Chemical
a. Extraction method
b. Absorption/Complexation
c. Ion exchange
d. Precipitation
e. Reduction
2) Physical
a. Filtration
b. Flocculation/Agglomeration
c. Adsorption
d. Molecular Sieve
e. Membrane Separation
3) Mechanical
a. Cyclone—Centrifugation
4) Biological
a. Plant—Phytoremediation
b. Bacteria
c. Enzyme—bioremediation
The above listed apparatus and methods are described in many documents including:    (1) Oekon, J. R. & Suyanto, P. T.: “Operating History of Arun Liquefied Natural Gas Plant,” SPE 12456, Journal of Petroleum Technology, May 1985, 863-867.    (2) Pongsiri, N.: “Initiatives on Mercury,” SPE Prod. & Facilities 14 (1), February 1999.    (3) Manchester, S. Wang, X., Kulaots, I. & Hurt, R. H.: “High Capacity Mercury Adsorption on Freshly Ozone-Treated Carbon,” NIH Public Access, PMC 2009, March 1.    (4) Mishra, S. P. & Vijaya,: “Inorganic Particulates in Removal of Heavy Metal Toxic Ions—Part X: Rapid and Efficient Removal of Hg (II) ions from Aqueous Solutions by Hydrous Ferric and Hydrous Tungsten Oxides,” Journal of Colloid Science 296 (2006) 383-388.    (5) Hsi, H. C., Rood, M. J., Abadi, M. R., Chen, S. & Chang, R.: “Mercury Adsorption Properties of Sulfur-Impregnated Adsorbents,” Journal of Environmental Engineering 128 (11) (Nov 2002) 1080-1089.    (6) Easterly L. A., Vass, A. A., Tyndall, R. L.: “Method for removal and recovery of Mercury”. U.S. Pat. No. 5,597,729, 1997.    (7) Li, Y. H., Lee, C. W., Gullett, B. K.,: Importance of Activated Carbon's Oxygen Surface Functional Groups on Elemental Mercury Adsorption.” Fuel, 2003; 82 (4) 451-457as well as the U.S. Pat. No. 6,537,444 to T. C. Frankiewicz and J. Gerlach and U.S. Pat. No. 5,460,643 to W. Hasenpusch and H. Wetterich among many others
Given that mercury can have a corrosive effect on tubing and other subterranean and surface production installation well before reaching any refinery, the known methods of scrubbing or removing it from the produced flow of hydrocarbon at the point of entry to the refining process can be regarded as a problem. In the light of these corrosive and other adverse effects on the operation of production installations in boreholes and the surface, it is seen as an object of the present invention to provide tools and methods to remove mercury as early as possible from the production stream.